nshemon
Newbie level 5
Hey guys, you helped me out several months ago with one of my problems, so I hope that you can help me with this also (it shouldn't be that hard).
So I am using the chip DS2016 for some external memory in my small project. When in operation, it will be plugged into the wall, and through a converter which will give the chip 5 Volts to run on. This is fine. But the chip also has the ability to run on lower power mode and so I have a smaller battery (3V) which I want to use as a battery backup when the board is unplugged from the wall. The problem, though, is that I don't want to keep the backup battery hooked up the entire time (since that would drain it).
It seems to me that a simple transistor would switch between the two power sources, but i can't get it to work out. I think my PNP transistor is not the correct type, and I don't think NPN transistors can do what I want. Both the NPN and PNP are from Radio Shack (for convenience) and the link to them are below.
h**p://www.radioshack.com/product/index.jsp?productId=2062586&cp=2032058.2032230.2032279&parentPage=family
h**p://www.radioshack.com/product/index.jsp?productId=2062585&cp=2032058.2032230.2032279&parentPage=family
Thanks for any help.
-nshemon
also here's a link to the chip:
h**p://www.maxim-ic.com/quick_view2.cfm/qv_pk/2835
So I am using the chip DS2016 for some external memory in my small project. When in operation, it will be plugged into the wall, and through a converter which will give the chip 5 Volts to run on. This is fine. But the chip also has the ability to run on lower power mode and so I have a smaller battery (3V) which I want to use as a battery backup when the board is unplugged from the wall. The problem, though, is that I don't want to keep the backup battery hooked up the entire time (since that would drain it).
It seems to me that a simple transistor would switch between the two power sources, but i can't get it to work out. I think my PNP transistor is not the correct type, and I don't think NPN transistors can do what I want. Both the NPN and PNP are from Radio Shack (for convenience) and the link to them are below.
h**p://www.radioshack.com/product/index.jsp?productId=2062586&cp=2032058.2032230.2032279&parentPage=family
h**p://www.radioshack.com/product/index.jsp?productId=2062585&cp=2032058.2032230.2032279&parentPage=family
Thanks for any help.
-nshemon
also here's a link to the chip:
h**p://www.maxim-ic.com/quick_view2.cfm/qv_pk/2835